Daemon program control script example (bash)

gistfile1.sh

#!/bin/bash

prgfile=<Program Script filepath>
pidfile=<PID filepath>

start() {
    if [ -f $pidfile ]; then
        pid=`cat $pidfile`
        kill -0 $pid >& /dev/null
        if [ $? -eq 0 ]; then
            echo "Daemon has started."
            return 1
        fi
    fi

    $prgfile

    if [ $? -eq 0 ]; then
        echo "Daemon started." 
        return 0
    else
        echo "Failed to start daemon."
        return 1
    fi
}

stop() {
    if [ ! -f $pidfile ]; then
        echo "Daemon not started."
        return 1
    fi

    pid=`cat $pidfile`
    kill $pid >& /dev/null
    if [ $? -ne 0 ]; then
        echo "Operation not permitted."
        return 1
    fi

    echo -n "Stopping daemon..."
    while true
    do
        kill -0 $pid >& /dev/null
        if [ $? -ne 0 ]; then
            break
        fi

        sleep 3
        echo -n "."
    done

    echo -e "\nDaemon stopped."
    return 0
}

status() {
    if [ -f $pidfile ]; then
        pid=`cat $pidfile`
        kill -0 $pid >& /dev/null
        if [ $? -eq 0 ]; then
            echo "Daemon running. (PID: ${pid})"
            return 0
        else
            echo "Daemon might crash. (PID: ${pid} file remains)"
            return 1
        fi
    else
        echo "Daemon not started."
        return 0
    fi
}

restart() {
    stop
    if [ $? -ne 0 ]; then
        return 1
    fi

    sleep 2

    start
    return $?
}

case "$1" in
    start | stop | status | restart)
        $1
        ;;
    *)
        echo "Usage: $0 {start|stop|status|restart}"
        exit 2
esac

exit $?